Exemplary embodiments of the present disclosure pertain to the art of rotary blade design and more specifically to a fan blade for a gas turbine engine having a frangible strip on a fan blade tip.
Engine manufactures may be concerned with maintaining tight clearances between fan blade tips and abradable rub strips in fan cases to achieve improved aerodynamic efficiency. Fan blade excitations in a fan module of a gas turbine engine are known and may result from various kinds of perturbing events, e.g., inflight encounters with birds, the decoupling of fan blades due to structural failures, and other known and observed causes. During a perturbing event a fan rotor centerline may shift away from the engine centerline due to induced vibratory motion and/or unbalanced impulses extending radially outward from the fan blade root towards the blade tip. As the rotor centerline shifts away from the engine centerline fan blades may be urged towards the fan case and fan blade tips may move towards abradable rub strips that line the inner surface of the fan case. As the fan blade tips and rub strips interact, the fan rotor may decelerate and generate large torques which are then reacted by the fan case and disbursed among the various engine static structures. There is a need to reduce the effect of the interaction between fan blade tips and rub strips when the rotor centerline shifts away from the engine centerline.